高地应力深埋隧道开挖扰动规律

Perturbing mechanism of excavation in high geostress and deep-buried tunnel

以颗粒离散元理论为基础,建立不同应力场作用下的大尺度深埋隧道模型,从开挖过程中的能量转换规律、应力波传播衰减规律及应力重分布规律等角度研究构造应力场对双线硬岩隧道的影响。结果表明:隧道瞬时开挖后,围岩系统的应变能、动能及耗散能均存在三阶段演化规律。侧压力系数越大,围岩受到的扰动越剧烈;侧压力系数小于1时,拱顶、拱底由于处于应力松弛区,无扰动波产生;拱腰处于应力加载区,卸荷后期会产生同向的第二峰值扰动波;侧压力系数为1时,无明显扰动波产生;侧压力系数大于1时,扰动波产生位置为拱顶、拱底处,且扰动波的方向与卸载波相反;应力卸荷过程可以分为剧烈扰动、卸荷调整以及卸荷完成3个阶段。

Based on the discrete element theory of particles,a large-scale deep-buried tunnel model was established for the energy transformation,stress wave attenuation and stress redistribution of surrounding rocks after tunnel excavation in different stress fields. Results showed that the strain energy,kinetic energy and dissipative energy of the surrounding rock system had three-stage evolution features after the instantaneously excavated period of tunnel. The larger the lateral pressure coefficient,the severer the disturbance of surrounding rock. When the lateral pressure coefficient was less than 1,the vault and arch base were in the stress relaxation zone with no disturbance waves,while the arch waist was in the stress loading zone and disturbance wave occured in the unloading stage. When the lateral pressure coefficient was 1,there was no obvious perturbation wave. When the lateral pressure coefficient was larger than 1,the disturbance wave occured in vault and arch,and the direction of disturbance wave was opposite to that of unloading wave. Stress unloading processes could be divided into three stages of severe disturbance stage,unloading adjustment stage and unloading completed stage.